Awesome project. While going over it to figure out how it worked, I looked up the 'cl' package and noticed that it has been deprecated in favor of cl-lib. [1] Also, what license (if any) does this fall under?
From the top of cl-lib.el in Emacs 25.1:
;;; cl-lib.el --- Common Lisp extensions for Emacs -*- lexical-binding: t -*-
;; Copyright (C) 1993, 2001-2016 Free Software Foundation, Inc.
;; Author: Dave Gillespie <daveg@synaptics.com>
;; Version: 1.0
;; Keywords: extensions
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.https://github.com/burtonsamograd/emacs-jit/blob/master/COPY... (GPL v3)
I see nothing else which overrides this but I could be mistaken.
Open raytracer.el
M-x eval-buffer
M-: (ray-test 256)